Can Halogen Clusters be Emissive?

Halogen-halogen short contacts, especially halogen bonds (XBs) have been widely utilized in multifarious fields, owing to its bridging function among luminophores as well as well-known heavy atom effect. However, little attention has been paid to the luminescent ability of halogen clusters. It remains unknown whether they are emissive. Herein, inspirited by the clustering-triggered emission of nonconventional luminophores, we report the first examples of emissive halogen clusters with fluorescence-phosphorescence dual emission in aggregated state and even under ambient conditions. Additionally, multi-tunable PL in response to excitation wavelength, temperature, and pressure are noticed. These results shed new lights on the underlying emission mechanism and would inspirit further exploration of nonconventional luminophores involving halogen moieties.